Advanced Materials Research Vols. 433-440

Abstract: recently, a modified Particle Swarm Optimizer (MLPSO) has been succeeded in solving truss topological optimization problems and competitive results are obtained. In order to reduce its execution time for solving large complex optimization problem, a parallel version for this optimizer (PMLPSO) is studied in this paper. This paper first gives an overview of PSO algorithm as well as the modified PSO, and then a design and an implementation of parallel PSO is proposed. Since most of structural problems involve discrete design variables, an effect strategy is involved in MLPSO in order to operate on discrete variables. The performance of the proposed algorithm is tested by two examples and promising speed-up rate is obtained. Final part is conclusion and outlook.

Abstract: This paper presents a wavelet packet selective algorithm to suppress the radio frequency interference (RFI) in the step-frequency ground-penetrating radar (SFGPR). Based on the property and the form of RFI in the frequency domain of radar echo, the methods of RFI suppression are studied, and the new algorithm is proposed. Using the new algorithm to suppress the RFI in experimental GPR data, the result of the experimentation shows that the algorithm can effectively suppress the RFI in SFGPR. Finally, the performance of the algorithm is analyzed and evaluated. Compared with the median filter algorithm, the ability of the new algorithm to suppress the RFI is significantly improved.

Abstract: In this paper, an improved cooperative MAC protocol which uses Multiplicative-Increase Linear-Decrease (MILD) backoff algorithm in the contention procedure to solve the fairness problem brought by Binary Exponential Backoff (BEB) is proposed for Wireless Local Area Network (WLAN). In order to improve the relay selection mode, the cooperative table in this improved cooperative MAC protocol is stored in the relay station, and we replace one field in it by the Destination ID. The simulation results show that the improved cooperative MAC protocol greatly enhances the throughput performance of the system and provides lower transmission delay in WLAN especially when there are few stations in the network.

Abstract: This paper demonstrates a method to update design revisions in the Platform Flash XCFP PROMs for configuration of Xilinx® FPGAs. The Platform Flash XCFP PROMs contain boundary-scan(JTAG) facilities that are compatible with IEEE Std 1149.1. Combining the FPGA configuration data (FPGA bitstream) into a PROM from GPIO ports of an embedded microcontroller through JTAG TAP interface of the PROM. The JTAG download method based on the GPIO ports of an embedded microcontroller can be implemented to erase, program, and verify the Platform Flash XCFP PROMs using IEEE Std 1149.1^[1]

Abstract: Aiming at the rationality of new knowledge mesh, which is obtained from the self-reconfiguration of knowledgeable manufacturing systems, the inherent structure principle of the knowledge mesh is studied. Firstly, the sets of the knowledge points are classified by the equivalent relations, and the function topological space is constructed. The relationships between the sets of the knowledge points and the function topological space are established by the real set. In the function topological space, the conclusions of the base are given, which show the essential mapping relationships of the knowledge mesh, the topological space and the base. After knowing the principle, the structure of the knowledge mesh is reduced by using the equivalent relations, the base and the basic knowledge points. The completeness of the complex relationships in the knowledge mesh is studied by the transitive closure. These conclusions can reduce the structure and enhance the rationality of the knowledge mesh. Finally the given example shows that these theories are effective.

Abstract: An improved algorithm (AFSA-IWO) was developed based on the artificial fish swarm algorithm (AFSA) and invasive weed optimization (IWO). It introduces IWO, and improves its mechanism of the competitive exclusion to meet practical application. Convergence analysis was performed with some typical benchmark test functions and comparison was made with AFSA. At the same time, it uses the AFSA-IWO to optimize the PID parameters. The results showed that the approach presented better ability in leaping over the local extremum and enhancing local exploration, and can void blind searching in the later evolution period. So it is a global optimization algorithm with good feasibility and high efficiency.

Abstract: When the scale of wind farm is increased quickly, if not considering the impedance of the collection system within wind farm, the bigger error in power flow calculation may be caused. In this paper a simple equivalence method calculating the collector system equivalence impedance by using the equivalence power loss is proposed and wind farm’s equivalence output power model considering wake effect and wind speed is established. The models are applied in power flow calculation of the natural wind farm connected to Urumqi grid, Xinjiang. The results compared with original system power flow show that this method has lower error. By using the losses in the collector system, the method of computing the equivalence impedance is verified in this paper. The equivalence impedance of collector system is calculated from total active power loss and total reactive power loss and current flow of the collector system. The error analysis showed that the equivalence impedance of collector system has lower error. The test results show that the proposed equivalence method is effective and logical and has a certain practicality. The reference is given for farther studying safety and stability operation of electric power system including wind farm.

Abstract: Parallel computation is an effective approach to real-time simulation and transient stability online assessment of large-scale power systems. In this paper, the s-stage 2s-order symplectic Runge-Kutta-Nyström method is adopted for transient stability simulation of power system using classic model. Using Butcher transformation, a new parallel algorithm has been derived. The proposed algorithm has the convergence characteristic of a Newton type method and is of fully parallel-in-time. Through numerical simulation where the IEEE 145-bus power system is used, the proposed algorithm has been tested and compared with the conventional parallel-in-time Newton approach using implicit trapezoidal rule.

Abstract: As the ± 800kV Xiangjiaba-Shanghai UHVDC pilot demonstration project has been completion production in China, an UHV AC and DC power era is coming in State Gird. A large number of calculations of main circuit steady state parameters for HVDC system are necessary for both HVDC transmission planning and design and checking DC projects in operation. Therefore, this paper firstly discusses the steady state parameters. Then considering the comprehensiveness of types of HVDC transmission, through digesting design features of foreign similar software, the steady state parameters calculation software for HVDC transmission is developed independently. It has features such as user-friendly interface, real-time calculation and calculation of comprehensive, rapid and accurate, using the mixed programming of Visual C++ (VC++) and MATLAB. Finally, take the ± 800kV Xiangjiaba-Shanghai UHVDC transmission project for example to calculate steady state parameters. The calculation results are accurate to meet the engineering requirements.

Abstract: The design of synopses structure is an important issue of frequent patterns mining over data stream. A data stream synopses structure FPD-Graph which is based on directed graph is proposed in this paper. The FPD-Graph contains list head node FPDG-Head and list node FPDG-Node. The operations of FPD-Graph consist of insert operation and deletion operation. A frequent pattern mining algorithm DGFPM based on sliding window over data stream is proposed in this paper. The IBM synthesizes data generation which output customers shopping a data are adopted as experiment data. The DGFPM algorithm not only has high precision for mining frequent patterns, but also has low processing time.